Search Documents

By William R. Yernberg

SME’s Arizona Conference was held at the Doubletree Hotel at Reid Park in Tucson on Dec. 4 and 5, 2005. The annual conference is organized by the Arizona Conference Board of Directors, which represents SME sections in Arizona and adjacent areas. The conference provides an opportunity for individuals and corporations associated with mining in the region to get together once each year to discuss the status of the industry. Important topics discussed among the attendees included the price of copper, community relations and education.

Jan 1, 2006

By E. Bakhtavar

Finding a ?practical spacing between the holes? for use of the expansive mortars is an important problem in dimension stone quarries. Objective has been to first introduce a relationship between this spacing and the dependent parameters in such a way that the required size and shape of the blocks is produced with the maximum efficiency and safety, minimum wastage, conservation of reserves and protection of environment. For this purpose, a dimensional analysis was used. On the basis of granite and marble rock types in Iran two separate relations are hence established to calculate the practical spacing between the holes.

Jan 1, 2011

By F. G. Heivilin

We are no longer short of viable Rare Earth deposits. As little as 2 years ago China mined and produced 97% ofthe world?s rare earths. Only a few deposits were in an advanced stage of exploration and development. Now Technical Metals Research (TMR) Gareth Hatch *5 reports that 347 deposits are being developed by 265 companies down from 440 on July 6th. Their Index of Advanced projects lists 45 projects in 14 countries. They will sustain the world for centuries to come and many good deposits are yet to be found. The problem is mining 14 elements in balance. Each of the deposits listing production in the chart has a unique set of minerals which they think will give them a cost advantage. Which of these will make it to production is a question. Most of the Advanced won?t be mined soon, but which ones? China is still in the driver?s seat in Light Rare Earth production (LREO) with one deposit with 35 million ton Baiyunebo deposit in Inner Mongolia which is part of a working iron ore deposit. The number of HREE deposits have been reduced and they attempting to eliminate unpermitted mines. This report will tell you what a Rare Earth is, how rare they are, why they are important, and where they are being developed which includes Australia, the United States, Africa, Greenland, Brazil and Canada.

Feb 27, 2013

In September 2003, a test was conducted to see if a115-mm- (4.5-in.-) diam Mocap Vari-Stem blasthole plug could improve the pattern of explosives using different top stemming material. The test took place at the J.S. Faulkroad and Sonsstone quarry in McCalisterville, PA. The test consisted of a production stone blast. Half of the holes were stemmed with standard crushed stone. Two-thirds of the remaining half were stemmed with Vari-Stem plugs and crushed stone. And the remaining one-third of the second 50 percent was stemmed with Vari-Stem plugs and only drill cuttings.

Jan 1, 2004

By Roger P. Ashley

The main problem in geochemical exploration for gold ore bodies in the 40 km2 hydrothermally altered area at Goldfield is to decide which of the many silicified ledges exposed are most likely to yield deposits with additional subsurface exploration. We conclude that the most efficient way to search for exploration targets is to collect rock samples from the ledges and analyze for the following elements in decreasing order of priority: gold, lead and silver, bismuth, and mercury. These elements form relict hypogene aureoles restricted to the ledges and are not appreciably redistributed during supergene leaching.

Jan 1, 1978

By Fritz Grübl

Modern shield TBMs allow tunnel drives through almost any type of ground. Thanks to high elaborated technical measures, significant subsidence of the ground surface can be almost entirely avoided. The tunnel lining behind the TBM must be capable of withstanding all loads without deforming, especially during ring erection and advance. Single-shell tunnel linings behind the TBM, usually reinforced concrete segmental rings, can be designed to fulfill this demand. With many projects, however, damage occurs to the lining. Repair costs may be extremely high. Reasons for damages and possibilities to avoid them are shown and explained.

Jan 1, 2001

By G. E. S. Valadao, J. D. Miller, C. L. Lin

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake poremicro structure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 m, length of 500 m and height of 4000 m. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: 1) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method,2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4)some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By M. R. Yalamanchili

Recently, noequilbrium electrokinetic measurements using laser-Doppler electrophoresis were reported by Miller et al. (1992) for alkali halides and the sign of their surface charge thus determined. These results are generally as expected from simplified lattice ion hydration theory with KCI, under normal circumstances, being the most significant exception. In this regard, lattice defects (F centers and oxygen imperfections) have been found to influence the surface charge of KCI and its electrophoretic mobility. In particular, the presence of oxygen defect states in the crystal lattice has been found to be responsible for KCI's unexpected behavior. The concentration of oxygen defect states in KCI, as characterized by UV/Vis absorption, was varied in order to study their influence on the electrokinetic behavior and subsequently on the flotation response of KCl. At low oxygen contents « 60 ppm) KCI is positively charged as expected from lattice ion hydration theory. However, typically, KCI contains substantial oxygen (>300 ppm) sufficient to impart a negative surface charge which accounts for the selective flotation of KCI from NaCl by hetero-coagulation with oppositely charged alkyl amine hydrochloride collector colloids.

Jan 1, 1994

By Gregory Yates

INTRODUCTION Project Description The Silver Line is a Bus Rapid Transit (BRT) Line and is Boston?s newest transit service. Silver Line Phase I extends along Washington Street entirely on the surface in priority bus lanes from Dudley Station in Roxbury through the South End and Chinatown neighborhoods to downtown Boston. The Phase I opened in July 2002. Silver Line Phase II consists of an underground transit tunnel from South Station to the South Boston Waterfront with underground stations at Courthouse and World Trade Center to Silver Line Way east of D Street. Phase II continues through the Ted Williams Tunnel to all the terminals at Logan Airport, and on the surface to the Boston Marine Industrial Park and City Point. Phase II opened in December 2004. Silver Line Phase III is a one mile tunnel connection to the existing Phase II tunnel in the vicinity of South Station and will eventually portal on Tremont Street just north of Marginal Road. After leaving the portal, the buses will use dedicated bus only lanes on the surface roadway network to connect to the Phase I service. Figure 1 shows the alignment of the Silver Line upon completion of the Phase III project.

By R. B. Pedersen, A. Filipa, A. Marques

"Shallow-depth (<200m) high temperature submarine hydrothermal systems are not commonly observed on mid-ocean ridge settings, as most known systems are located within arc - island-arc volcanic settings, often proximal to coastal areas (meteoric waters added). In 2013, during the Centre for Geobiology’s 2013 oceanographic cruise (R/V G.O. Sars), a dredge successfully sampled massive sulfides and hydrothermally altered rocks from the top of a volcanic edifice (~144-284 m depth) located on the northern sector of the Kolbeinsey Ridge. Dredged samples include vesicular altered basalts, and matrix supported anhydrite, barite and barite-pyrite-anhydrite volcaniclastic breccias. Sulfidesulfate breccias depict complex zoning where numerous small vent orifices are distributed with large blades of marcasite that appear intergrown with barite. Native sulfur was observed in one of these small vent orifices. On a microscopic scale, numerous spherical silica-rich structures appear associated to these breccias. These rocks are evidence for the presence of a relatively high temperature (minimum 150ºC) shallow-water seafloor hydrothermal system in the Arctic mid-ocean ridge, far from mainland influence. This new discovery presents a unique opportunity to study the dynamics of fluid chemistry, metal mobility and precipitation in shallow hydrothermal systems. The remote location of this system dictates that fluid recharge will be influenced solely by seawater and magmatic fluids, In July-August 2014 we expect to survey this new field and acquire new and comprehensive data."

Sep 1, 2014

Continued market pressure on the US coal industry was the overriding factor affecting developments in underground mining in 1986. An oversupply of coal in the spot market kept prices low throughout the year and caused a number of operations to close their doors. Operators stepped up their efforts to improve productivity at existing operations. They made technology advances and improved their relations with employees. A continuing market-related development during 1986 was the divesting of coal properties and operations by major oil companies, which were faced with economic pressures in both the oil and coal industries. Further increases in contract mining production resulted as some larger operators were unable to compete in a tough economic environment. Longwall mining is still seen by many as the technology that will provide the necessary productivity to remain cost-effective. But the number of active faces in the US declined in 1986, as reserves were depleted and economics forced some closures. At the first Longwall USA meeting in June, much attention was placed on improved technology, as electro-hydraulic controls for roof supports gained acceptance. Other recent developments include shearer initiation of roof supports, automatic horizon control for shearer drums, and collection and storage of machine data for predicting maintenance requirements. The government and academic communities continued their research on dust control at longwall faces. Jankowski, Kissel, and Daniel, (October 1986, Mining Engineering), gave an overview of progress in longwall dust control. And Mukherjee, Singh and Jayarman (November 1986, Mining Engineering), recommended design guidelines for improving water spray systems for dust control. Surface subsidence Increasing attention is being given to surface subsidence. This is primarily because of longwall mining and the Surface Mining Control and Reclamation Act. Improved methods of prediction of surface subsidence, especially computerized methods, are being continually developed. Mining engineering faculty at major universities such as Virginia are helping develop public policy and regulations concerning subsidence. As part of this effort, Unrug and Johnson identified major subsidence areas of Western Kentucky. Peng and Chen (February 1986, Mining Engineering), gave an overview of history and research of surface subsidence. And Elifrits and Aughenbaugh, (February 1986, Mining Engineering), discussed effects of moisture variations and overburden on subsidence. This research culminated in a Symposium on Surface Subsi¬dence at the SME 1986 Fall Meeting in St. Louis and the 2nd Workshop on Surface Subsidence at West Virginia University. Ground control in coal mining continued to be an item of major research interest. Some 30 papers were presented at the 5th International Conference on Ground Control in Mining at West Virginia University. And six sessions were related to coal mining at the 27th US Symposium on Rock Mechanics at the University of Alabama. At the 4th Annual Workshop, Generic Mineral Technology Center, Mine Systems Design and Ground Control emphasized efforts of the participating universities to improve ground control. Peng and Chiang summarized results of studying support capacity and roof behavior with longwall shield supports. And Unrug, Johnson, and Nandy analyzed the process of deterioration of shale roof in a case study of a room-and-pillar coal mine. The importance of geologic conditions in determining mining productivity is receiving increased attention in coal mine design in the US. Mullenex related, through case studies, the benefits to be derived through analyzing the depositional system of coalbeds as an integral part of mine design. Improved technology in this area was related by Lloyd, Semborski, and Stolarczyk. They discussed a case study of using radio imaging to indicate coal-seam discontinuities in advance of mining. Improved coal mining technology in general is being researched more heavily, to help improve US coal competitiveness. However, much of this research and development process has yet to be widely implemented. Equipment manufacturers are devoting more resources to development of continuous-haulage systems, mobile roof-supports, mine-monitoring systems, and predictive-maintenance systems using computers to extract machine data.

Jan 5, 1987

By R. J. Pruett

The Georgia kaolin district is the world’s largest producer of kaolin. Georgia production tripled from 2.87 Mt (3.17 million st) in 1968 to8.35 Mt (9.2 million st) in 1998. Development of the Georgia kaolin industry can be traced to the identification of the mineral resource, the adoption of innovative process technologies and the creation of markets for kaolin. Georgia kaolin is an abundant and high-quality resource that shows a range of advantageous properties. Technical developments in wet processing, delamination and calcination allowed production of high-value products. The use of kaolin pigments in the paper industry provided a market that absorbed the rapid growth in kaolin production.

Jan 1, 2000

By R. K. Jade

Although several studies in combining and bifurcating flows in two-way junctions and splits are reported, deviations persist in the estimated shock loss coefficients (SLCs). Due to their complex nature, more work has to be done to be able to correctly predict flow losses at these locations. In two-way splits, the flow at bifurcation is known to be characterized mainly by two recirculating zones in the downstream branches, whereas, in a junction one recirculating zone is observed immediately downstream of the main branch. The relative flow rate in the branches (quantity ratios) is treated as the only parameter defining the losses at these locations. However, the effect of wall roughness, if any, on SLCs becomes important for mine ventilation. This paper presents the critical determinants of shock losses at splits and junctions at varying quantity ratios. The flow at 90º split and junction was examined both experimentally and numerically for Reynolds number in the range of 1.0×104 to 1.6×105. With a well designed laboratory setup, using precision instruments, velocity and pressure measurements were carried out, by using two scales of wall roughness. 3D numerical simulations for these experiments were conducted by using ANSYS CFX modeling tool. CFD simulations yielded results that are reasonably close to experiments, providing high degree of satisfaction in numerically predicting losses across the splits and junctions. However, comparisons of these numerical simulation results with existing literature standards showed significant under-estimation of shock losses by the standard literature by as much as 50%. A clear rise in the magnitude of shock losses was noted in both the approaches, with increased wall roughness. Based on the current studies, predictor equations incorporating quantity ratios are developed for accurate estimation of shock losses. Further investigations on roughness are needed, before one is able to incorporate wall roughness into the prediction of SLC.

Jan 1, 2009

By K. Hopperstead

Ventilation planning in trackless metal mining is often taken for granted. This paper highlights the trials of planning and executing the ventilation design for Bog Zone at the Lisheen Mine. Ventilation planning for Bog Zone started at the feasibility study stage in 2003; subsequent design changes continued until 2006. In August 2006, the development of the Bog Zone ore body was accelerated through the use of contractors; in addition, the Lisheen equipment fleet was revised based on a larger load and haul fleet. As a result, the circuit was reviewed in terms of changes in design conditions and best practices. This review resulted in a 40% increase of total airflow required to mine Bog Zone. Resources utilized to design the circuit include: external review, computer modeling, and in-house Lisheen planning and operational staff review. The final ventilation design configuration was adopted in 2007, after modeling and evaluating 30 different scenarios, resulting in a better distribution of airflow, optimized secondary escape way, reduced contaminants, and a total power reduction. The value of investment in computer modeling of primary ventilation circuit and planning for staged implementation should never be underestimated.

Jan 1, 2009

By T. Hudaverdi

Several studies have been conducted on blastability and prediction of fragmentation. The term blastability is used to refer the susceptibility of the rock to blasting and is closely related to fragmentation. Parameters that determine fragmentation by blasting may be divided into two groups. The first group consists of blasting design parameters. The blast design parameters are controllable parameters and determined by the explosive engineers. The burden, spacing between holes, bench height, drillhole diameter, stemming height and explosive density are all design parameters. The second group consists of rock mass parameters that are referred to as uncontrollable parameters. The uncontrollable parameters are physical and mechanical properties of rock and rock mass structure. The strength, modulus of elasticity, density of rock, number of joint sets, joint orientation and joint spacing are among uncontrollable parameters. The rock mass parameters and blast design parameters should be considered together to explain fragmentation process. In this study, a blast database was accumulated to use for multivariate analysis. The blast database contains the blasts performed near Istanbul region quarries and the blasts that were preformed in various mines in the world by the blasting researchers. The cluster analysis was used to separate the blast data into different similarity groups. Group memberships were analyzed and checked by the discriminant analysis. Then, the multivariate regression analysis was used to develop a prediction equation for blast fragmentation for each group. Finally, a validation of the suggested models was performed for various mines. The model comprises blast design parameters, mechanical properties of rock and rock mass structure.

Jan 1, 2011

By Mark J. Zdunczyk

"The term “aggregate” has a number of definitions depending primarily on the use of the material. Aggregate in some context is sand, gravel, crushed stone, slag or other material of mineral composition used in bituminous and portland cement concrete, mortar, plaster, railroad ballast, filter beds and a variety of other uses where aggregates can be utilized.Of the natural aggregates, crushed stone is widely used for most construction purposes. Crushed stone can be mined from a variety of rock types such as limestone, dolomite (dolostone), granites, and granitic type rocks, basalt, gabbro (trap rock), sandstones, schist, marble, gneiss, quartzite, rhyolite, as well as other rock types. The U.S. Geological Survey (USGS) breaks down the rocks by type sold as follows: limestone, dolomite, marble, calcareous marl, shell, granite, trap rock (basalt, diorite) sandstone/quartzite, slate, volcanic cinder and scoria and miscellaneous stone.In 2015, the USGS estimates that 1.32 Gt (1.45 billion st) of crushed stone were produced in the United States. The volume of crushed stone produced, and the numerous mines that produce it make the crushed stone industry the largest mining industry in the United States. The five leading states for production of crushed stone in 2015 were Texas, Pennsylvania, Missouri, Florida and Ohio. The size of the first two states certainly helps in output because of the large market area. The remaining states benefit from being able to barge along rivers to outside markets in adjoining states. Georgia producers rail large amounts of granitic aggregate to Florida and adjacent states devoid of crushed stone aggregate, especially skid resistant aggregate (aggregate used on the top course of asphalt roads)."

Jul 1, 2016

By R. Q. Honaker, D. P. Patil, A. Sirkeci

Due to increased production of fine coal during mining during this century and inefficient fine coal recovery technologies, a vast reserve of high quality coal currently exists in refuse ponds. A novel fine coal circuit consisting of a hindered-bed classifier, an enhanced gravity concentrator and a flotation column has been evaluated for the recovery of fine coal from refuse ponds. The treatment of a pond derived from Pittsburgh No. 8 seam coal resulted in the production of a premium fuel containing less than 5% ash and a calorific value of about 30,173kJ/kg with 60% mass yield. The results from the treatment of two refuse pond materials will be presented in this publication.

Jan 1, 2000

By C. G. Buttleman, W. C. Brice

In Minnesota, reclamation of active aggregate mining sites is primarily regulated through local permits issued at the county, township, or municipality. However, for abandoned or depleted aggregate mining sites, a responsible party for reclamation is often no longer available. Since 1995, the Minnesota Department of Natural Resources has reclaimed several abandoned aggregate sites using innovative public/private partnerships and emphasizing native plant materials. The purpose of these projects is to demonstrate cost effective reclamation methods that can be utilized by both aggregate operators and local government and to promote mine planning and resource identification as it relates to reclamation.

Jan 1, 2000

By G. Kim

The influence of bacterial growth phase on the flotation behavior of malachite has been investigated in a well-controlled Hallimond tube system. The microflotation tests were conducted for malachite (45?53 µm) using different amounts (bulk phase concentration=1×108?5×109 cells/mL) of Rhodococcus opacus (R. opacus) as a collector, which was grown at mid-exponential versus stationary phase, at a constant speed (340 rpm), pH (6), and malachite-bacteria interaction and flotation time (each 10 min). Hug differences between R. opacus cells in mid-exponential and stationary phase was observed from the results for electrophoretic mobility and flotation tests. Specifically, the isoelectric point of the cells in the stationary phase was lower than that in the mid-exponential phase, suggesting that the amount and distribution of surface functional groups onto cell surfaces are likely different. Additionally, the cells in stationary phase led to significant increase in the flotability compared to those in mid-exponential phase over the background bacterial concentration level of 1×108?5×109 cells/mL. Furthermore, the flotation efficiency tended to increase with increasing cell dosage for stationary phase cells while no distinct difference was observed for mid-exponential cells.

Feb 27, 2013

According to the previous research, it is found that the thickness of cover is mostly less than 100 m for highwall mining system. However, for most of the Chinese surface coal mines, the mining depth is over 150 m; on the other hand, the shovel-truck is the most common mining technology. As a result, a lot of residual coal will be remained around end-walls. Considering these facts, the calculated methodology of highwall mining system under thick cover is presented in this paper. Meanwhile, numerical simulation of highwall mining system under thick cover was carried out. The outcome shows that the calculated methodology for pillar stability of highwall mining system under thick cover presented in this paper is acceptable. In other words, the highwall mining system is feasible to extract the residual coal around end-walls in Chinese surface coal mines. Thus, not only coal recovery ratio can be improved, but also can increase the production life of surface coal mines in China.

Jan 1, 2012